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IS 1893 ( Part 1 ) :2002, , Indian Standard, CRITERIA FOR EARTHQUAKE RESISTANT, DESIGN OF STRUCTURES, PART 1 GENERAL, (, , PROVISIONS, , Ffth, , AND BUILDINGS, , Revision ), , ICS 91.120.25, , 0 BIS 2002, , BUREAU, , OF, , INDIAN, , STANDARDS, , MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG, NEW DELHI 110002, June 2002, , —.., , Price Group 12

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IS 1893( Part 1 ) :2002, , Indian Standard, CRITERIA FOR EARTHQUAKE RESISTANT, DESIGN OF STRUCTURES, PART 1 GENERAL, (, , PROVISIONS, , AND BUILDINGS, , Fijth Revision ), , FOREWORD, This Indian Standard ( Part 1 ) ( Fifth Revision) was adopted by the Bureau of Indian Standards, afler the, draft finalized by the Earthquake Engineering Sectional Committee had been approved by the Civil Engineering, Division Council., Himalayan-Nagalushai region, Indo-GangeticPlain, Western India, Kutch and Kathiawarregions are geologically, unstable parts of the country, and some devastating earthquakes of the world have occurred there. A major, part of the peninsular India has also been visited by strong earthquakes, but these were relatively few in, number occurring at much larger time intervals at any site, and had considerably lesser intensity. The earth@ake, resistant design of structures taking into account seismic data from studies of these Indian earthquakes has, become very essential, particularly in view of the intense construction activity all over the country. It is to, serve this purpose that IS 1893 : 1962 ‘Recommendations for earthquake resistant design of structures’ was, published and revised first time in 1966., As a result of additional seismic data collected in India and further knowledge and experience gained since, the publication of the first revision of this standard, the sectional committee felt the need to revise the standard, again incorporating many changes, such as revision of maps showing seismic zones and epicentres, and adding, a more rational approach for design of buildings and sub-structures of bridges. These were covered in the, second revision of 1S 1893 brought out in 1970., As a result of the increased use of the standard, considerable amount of suggestions were received for modifying, some of the provisions of the standard and, therefore, third revision of the standard was brought out in 1975., The following changes were incorporated in the third revision:, a), , The standard incorporated seismic zone factors (previously given as multiplying factors in the second, revision ) on a more rational basis., , b), , Importance factors were introduced to account for the varying degrees of importance for various, structures., , c), , In the clauses for design of multi-storeyed buildings, the coefficient of flexibility was given in the, form of a curve with respect to period of buildings., , d), , A more rational formula was used to combine modal shear forces., , e), , New clauses were introduced for determination of hydrodynamic pressures in elevated tanks., , 8, , Clauses on concrete and masonry dams were modified, taking into account their dynamic behavionr, during earthquakes. Simplified formulae for design forces were introduced based on results of extensive, studies carried out since second revision of the standard was published., , The fourth revision, brought out in 1984, was prepared to modifi some of the provisions of the standard as a, result of experience gained with the use of the standard. In this revision, a number of important basic modifications, with respect to load factors, field values of N, base shear and modal analysis were introduced. A new concept, of performance factor depending on the structural framing system and on the ductility of construction was, incorporated. Figure 2 for average acceleration spectra was also modified and a curve for zero percent damping, incorporated., , 1

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IS 1893( Part 1 ) :2002, In the fifth revision, with a view to keep abreast with the rapid development and extensive research that has, been carried out in the field of earthquake resistant design of various structures, the committee has decided, to cover the provisions for different types of structures in separate parts. Hence, IS 1893 has been split into, the following five parts:, Part 1 General provisions and buildings, Part 2 Liquid retaining tanks — Elevated and ground supported, Part 3 Bridges and retaining walls, Part 4 Industrial structures including stack like structures, Part 5 Dams and embankments, Part 1 contains provisions that are general in nature and applicable to all structures. Also, it contains provisions, that are specific to buildings only. Unless stated otherwise, the provisions in Parts 2 to 5 shall be read necessarily, in conjunction with the general provisions in Part 1., NOTE — Pending finalization of Parts 2 to 5 of IS 1893, provisions of Part 1 will be read along with the relevant, clauses of IS 1893 : 1984 for structures other than buildings., , The following are the major and important moditlcations made in the fifth revision:, a), , The seismic zone map is revised with only four zones, instead of five. Erstwhile Zone I has been, merged to Zone 11. Hence, Zone I does not appear in the new zoning; only Zones II, 111,IV and V do., , b), , The values of seismic zone factors have been changed; these now reflect more realistic values of, effective peak ground acceleration considering Maximum Considered Earthquake ( MCE ) and service, life of structure in each seismic zone., , c), , Response spectra are now specified for three types of founding strata, namely rock and hard soil,, medium soil and soft soil., , d), , Empirical expression for estimating the fundamental natural period Ta of multi-storeyed buildings, with regular moment resisting frames has been revised., , e), , This revision adopts the procedure of first calculating the actual force that maybe experienced by, the structure during the probable maximum earthquake, if it were to remain elastic. Then, the concept, of response reduction due to ductile deformation or frictional energy dissipation in the cracks is, brought into the code explicitly, by introducing the ‘response reduction factor’ in place of the earlier, performance factor., , f), , A lower bound is specified for the design base shear of buildings, based on empirical estimate of the, fimdarnental natural period Ta., , @ The soil-foundation system factor is dropped. Instead, a clause is introduced to restrict the use of, foundations vulnerable to differential settlements in severe seismic zones., h), , Torsional eccentricity values have been revised upwards in view of serious darnages observed in, buildings with irregular plans., , J), , Modal combination rule in dynamic analysis of buildings has been revised., , k), , Other clauses have been redrafted where necessary for more effective implementation., , It is not intended in this standard to lay down regulation so that no structure shall suffer any damage during, earthquake of all magnitudes. It has been endeavored to ensure that, as far as possible, structures are able, to respond, without structural darnage to shocks of moderate intensities and without total collapse to shocks, of heavy intensities. While this standard is intended for the earthquake resistant design of normal structures,, it has to be emphasized that in the case of special structures, such as large and tall dams, long-span bridges,, major industrial projects, etc, site-specific detailed investigation should be undertaken, unless otherwise specified, in the relevant clauses., , 2

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IS 1893( Part 1 ): 2002, Though the basis for the design of different types of structures is covered in this standard, it is not implied, that detailed dynamic analysis should be made in every case. In highly seismic areas, construction of a type, which entails hea~y debris and consequent loss of life and property, such as masonry, particularly mud masonry, and rubble masonry, should preferably be avoided. For guidance on precautions to be observed in the construction, of buildings, reference maybe made to IS 4326, IS 13827 and IS 13828., Earthquake can cause damage not only on account of the shaking which results from them but also due to, other chain effects like landslides, floods, fires and disruption to communication. It is, therefore, important to, take necessary precautions in the siting, planning and design of structures so that they are safe against such, secondary effects also., The Sectional Committee has appreciated that there cannot bean entirely scientific basis for zoning in view, of the scanty data available. Though the magnitudes of different earthquakes which have occurred in the, past are known to a reasonable degree of accuracy, the intensities of the shocks caused by these earthquakes, have so far been mostly estimated by damage surveys and there is little instrumental evidence to corroborate, the conclusions arrived at. Maximum intensity at different places can be fixed on a scale only on the basis of, the observations made and recorded after the earthquake and thus a zoning map which is based on the maximum, intensities arrived at, is likely to lead in some cases to an incorrect conclusion in view of(a) incorrectness in, the assessment of intensities, (b) human error in judgment during the damage survey, and (c) variation in, quality and design of structures causing variation in type and extent of damage to the structures for the same, intensity of shock. The Sectional Committee has therefore, considered that a rational approach to the problem, would be to arrive at a zoning map based on known magnitudes and the known epicentres ( see Annex A ), assuming all other conditions as being average and to modifi such an idealized isoseismal map in light of, tectonics ( see Annex B ), lithology ( see Annex C ) and the maximum intensities as recorded from damage, surveys. The Committee has also reviewed such a map in the light of the past history and future possibilities, and also attempted to draw the lines demarcating the different zones so as to be clear of important towns,, cities and industrial areas, after making special examination of such cases, as a little modification in the zonal, demarcations may mean considerable difference to the economics of a project in that area. Maps shown in, Fig. 1 and Annexes A, B and C are prepared based on information available upto 1993., In the seismic zoning map, Zone I and II of the contemporary map have been merged and assigned the level, of Zone 11. The Killari area has been included in Zone III and necessary modifications made, keeping in view, the probabilistic hazard evaluation. The Bellary isolated zone has been removed. The parts of eastern coast, areas have shown similar hazard to that of the Killari area, the level of Zone II has been enhanced to Zone III, and connected with Zone III of Godawari Graben area., The seismic hazard level with respect to ZPA at 50 percent risk level and 100 years service life goes on, progressively increasing from southern peninsular portion to the Himalayan main seismic source, the revised, seismic zoning map has given status of Zone III to Narmada Tectonic Domain, Mahanandi Graben and Godawari, Graben. This is a logical normalization keeping in view the apprehended higher strain rates in these domains, on geological consideration of higher neotectonic activity recorded in these areas., Attention is particularly drawn to the fact that the intensity of shock due to an earthquake could vary locally, at anyplace due to variation in soil conditions. Earthquake response of systems would be affected by different, types of foundation system in addition to variation of ground motion due to various types of soils. Considering, the effects in a gross manner, the standard gives guidelines for arriving at design seismic coet%cients based, on stiffness of base soil., It is important to note that the seismic coefficient, used in the design of any structure, is dependent on nany, variable factors and it is an extremely difficult task to determine the exact seismic coefficient in each given, case. It is, therefore, necessa~ to indicate broadly the seismic coefficients that could generally be adopted, in different parts or zones of the country though, of course, a rigorous analysis considering all the factors, involved has to be made in the case of all important projects in order to arrive at a suitable seismic coeftlcients, for design. The Sectional Committee responsible for the formulation of this standard has attempted to include, a seismic zoning map (see Fig. 1 ) for this purpose. The object of this map is to classifi the area of the country, into a number of zones in which one may reasonably expect earthquake shaking of more or less same maximum, intensity in future. The Intensity as per Comprehensive Intensity Scale ( MSK64 ) ( see Annex D ) broadly, associated with the various zones is VI ( or less ), VII, VIII and IX ( and above ) for Zones II, III, IV and V, respectively. The maximum seismic ground acceleration in each zone cannot be presently predicted with, 3

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IS 1893( Part 1 ) :2002, accuracy either on a deterministic or on a probabilistic basis. The basic zone factors included herein are, reasonable estimates of effective peak ground accelerations for the design of various structures covered in, this standard. Zone factors for some important towns are given in Annex E., Base isolation and energy absorbing devices may be used for earthquake resistant design. Only standard, devices having detailed experimental data on the performance should be used. The designer must demonstrate, by detailed analyses that these devices provide sufficient protection to the buildings and equipment as envisaged, in this standard. Performance of locally assembled isolation and energy absorbing devices should be evaluated, experimentally before they are used in practice. Design of buildings and equipment using such device should, be reviewed by the competent authority., Base isolation systems are found usefhl for short period structures, say less than 0.7s including soil-structure, interaction., In the formulation of this standard, due weightage has been given to international coordination among the, standards and practices prevailing in different countries in addition to relating it to the practices in the field, in this country. Assistance has particularly been derived from the following publications:, a), , UBC 1994, Uniform Building Code, International Conference of Building Officials, Whittier, Ckdifomia,, U.S.A.1994., , b), , NEHRP 1991, NEHRP Recommended Provisions for the Development of Seismic Regulations for New, Buildings, Part 1: Provisions,ReportNo. FEMA 222, Federal EmergencyManagement Agency,WashingtO%, D.C., U.S.A., January 1992., , c), , NEHRP 1991, NEHRP Recommended Provisions for the Development of Seismic Regulations for New, Buildings, Part 2: Commentary, Report No. FEMA 223, Federal Emergency Management Agency,, Washington, D. C., U. S.A., January 1992., , d) NZS 4203:1992, Code of Practice for General Structural Design and Design Loadings for Buildings,, Standards Association of New Zealand, Wellington, New Zealand, 1992., In the preparation of this standard considerable assistance has been given by the Department of Earthquake, Engineering, University of Roorkee; Indian Institute of Technology, Kanpuq IIT Bombay, Mumbai; Geological, Survey of India; India Meteorological Department, and several other organizations., The units used with the items covered by the symbols shall be consistent throughout this standard, unless, specifically noted otherwise., The composition of the Committee responsible for the formulation of this standard is given in Annex F., For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with, IS 2:1960 ‘Rules for rounding off numerical values ( revised )’. The number of signflcant places retained in, the rounded off value should be the same as that of the specified value in this standard., , (Earthquake Engineering Sectional Committee, CED 39 ), 4

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IS 1893( Part 1 ): 2002, , Indian Standard, CRITERIA FOR EARTHQUAKE RESISTANT, DESIGN OF STRUCTURES, PART 1 GENERAL, , PROVISIONS, , ( Ffth, , AND BUILDINGS, , Revision ), Title, , IS No., , 1 SCOPE, 1.1 This standard ( Part 1 ) deals with assessment of, seismic loads on various structures and earthquake, resistant design of buildings. Its basic provisions, are applicable to buildings; elevated structures;, industrial and stack like structures; bridges; concrete, masonry and earth dams; embankments and retaining, walls and other structures., , 1343:1980, , Code of practice for pre-stressed, concrete (first revision ), , 1498:1970, , Classification and identification of, soils for general engineering, purposes (first revision ), , 1888:1982, , Method of load test on soils (second, revision, , ), , 1.2 Temporary elements such as scaffolding, temponuy, excavations need not be designed for earthquake, forces., , 1893 (Part4), , 1.3 This standard does not deal with the construction, features relating to earthquake resistant design in, buildings and other structures. For guidance on, earthquake resistant construction of buildings,, reference may be made to the following Indian, Standards:, , Criteria for earthquake resistant, design of structures: Part 4 Industrial, structures including stack like, structures, , 2131:1981, , Method of standard penetration test, for soils (first revision ), , 2809:1972, , Glossary of terms and symbols, relating to soil engineering ( jirst, , IS 4326,1S 13827, IS 13828,IS 13920and IS 13935., , revision ), , 2 REFERENCES, 2.1 The following Indian Standards are necessary, adjuncts to this standard:, Is No., , 456:2000, , Code of practice for plain and, ( fourth, reinforced, concrete, , 4326:1993, , Earthquake resistant design and, construction of buildings — Code, of practice ( second revision ), , 6403:1981, , Code of practice for determination, of bearing capacity of shallow, foundations (first revision ), , 13827:1993, , Improving earthquake resistance of, earthen buildings — Guidelines, , 13828:1993, , Improving earthquake resistance of, low strength masonry buildings —, Guidelines, , 13920:1993, , Ductile detailing of reinforced, concrete structures subjected to, seismic forces — Code of practice, , 13935:1993, , Repair and seismic strengthening of, buildings — Guidelines, , SP 6 ( 6 ) :1972, , Handbook for structural engineers:, Application of plastic theory in, design of steel structures, , ), , Code of practice for general, construction in steel ( second, revision ), , 875, , Glossary of terms relating to soil, dynamics (fzrst revision), , Title, , revision, , 800:1984, , 2810:1979, , Code of practice for design loads, ( other than earthquake ) for buildings, and structures:, , (Part l): 1987 Dead loads — Unit weights of, building material and storedmaterials, ( second revision), (Part 2):1987, , Imposed loads ( second revision), , (Part 3):1987, , Wind loads ( second revision), , (Part4 ):1987, , Snow loads ( second revision), , (Part 5):1987, , Special loads and load combinations, ( second revision), 7, , PrT-’!?

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IS 1893( Part, , ) :2002, , 3.11 Effective Peak Ground Acceleration ( EPGA ), , 3 TERMINOLOGY FOR EARTHQUAKE, , ENGINEERING, , It is O.4 times the 5 percent damped average spectral, acceleration between period 0.1 to 0.3 s. This shall, be taken as Zero Period Acceleration ( ZPA )., , 3.1 For the purpose of this standard, the following, definitions shall apply which are applicable generally, to all structures., , 3.12 Floor Response Spectra, , NOTE — For the definitions of terms pertaining to soil, mechanics and soil dynamics references may be made, to IS 2809 and IS 2810., , 3.2 Closely-Spaced, , Floor response spectra is the response spectra for a, time history motion of a floor. This floor motion time, history is obtained by an analysis of multi-storey, building for appropriate material damping values, subjected to a specified earthquake motion at the base, of structure., , Modes, , Closely-spaced modes of a structure are those of its, natural modes of vibration whose natural frequencies, differ from each other by 10 percent or less of the, lower frequency., , 3.13 Focus, The originating earthquake source of the elastic waves, inside the earth which cause shaking of ground due, to earthquake., , 3.3 Critical Damping, The damping beyond which the free vibration motion, will not be oscillatory., , 3.14 Importance Factor (1), It is a factor used to obtain the design seismic force, depending on the functional use of the structure,, characterised by hazardous consequences of its failure,, its post-earthquake functional need, historic value,, or economic importance., , 3.4 Damping, The effect of internal friction, imperfect elasticity of, material, slipping, sliding, etc in reducing the amplitude, of vibration and is expressed as a percentage of critical, damping., 3.5 Design Acceleration, , 3.15 Intensity of Earthquake, , Spectrum, , The intensity of an earthquake at a place is a measure, of the strength of shaking during the earthquake, and, is indicated by a number according to the modified, Mercalli Scale or M. S.K. Scale of seismic intensities, (see AnnexD )., , Design acceleration spectrum refers to an average, smoothened plot of maximum acceleration as a fimction, of frequency or time period of vibration for a specitled, damping ratio for earthquake excitations at the base, of a single degree of freedom system., 3.6 Design Basis Earthquake, , 3.16 Liquefaction, , ( DBE ), , Liquefaction is a state in saturated cohesionless soil, wherein the effective shear strength is reduced to, negligible value for all engineering purpose due to, pore pressure caused by vibrations during an, earthquake when they approach the total confining, pressure. In this condition the soil tends to behave, like a fluid mass., , It is the earthquake which can reasonably be expected, to occur at least once during the design life of the, structure., 3.7 Design Horizontal, , Acceleration, , Coefficient, , (Ah), , 3.17 Lithological, , It is a horizontal acceleration coefficient that shall be, used for design of structures., 3.8 Design Lateral, , Features, , The nature of the geological formation of the earths, crust above bed rock on the basis of such characteristics, as colour, structure, mineralogical composition and, grain size., , Force, , It is the horizontal seismic force prescribed by this, standard, that shall be used to design a structure., , 3.18 MagnitudeofEarthquake, , ( Richter% Magnitude), , 3.9 Ductility, The magnitude of earthquake is a number, which is a, measure of energy released in an earthquake. It is, defined as logarithm to the base 10 of the maximum, trace amplitude, expressed in microns, which the, standard short-period torsion seismometer ( with a, period of 0.8s, magnification 2800 and damping nemly, critical ) would register due to the earthquake at an, epicentral distance of 100 km., , Ductility of a structure, or its members, is the capacity, to undergo large inelastic deformations without, significant loss of strength or stiffness., 3.10 Epicentre, The geographical point on the surface of earth vertically, above the focus of the earthquake., 8

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IS 1893( Part 1 ) :2002, idealized single degree freedom systems having certain, period and damping, during earthquake ground, motion. The maximum response is plotted against the, undamped natural period and for various damping, values, and can be expressed in terms of maximum, absolute acceleration, maximum relative velocity, or, maximum relative displacement., , 3.19 Maximum Considered Earthquake ( MCE ), The most severe earthquake effects considered by, this standard., 3.20 Modal Mass ( lf~ ), Modal mass of a structure subjected to horizontal or, vertical, as the case maybe, ground motion is apart, of the total seismic mass of the structure that is effective, in mode k of vibration. The modal mass for a given, mode has a unique value irrespective of scaling of, the mode shape., 3.21 Modal Participation, , 3.28 Seismic Mass, It is the seismic weight divided by acceleration due, to gravity., 3.29 Seismic Weight (W), , Factor ( Pk), , It is the total dead load plus appropriate amounts of, specified imposed load., , Modal participation factor of mode k of vibration is, the amount by which mode k contributes to the overall, vibration of the structure under horizontal and vertical, earthquake ground motions. Since the amplitudes of, 95 percent mode shapes can be scaled arbitrarily, the, value of this factor depends on the scaling used for, mode shapes., , 3.30 Structural, , Response Factors ( S,/g ), , It is a factor denoting the acceleration response, spectrum of the structure subjected to earthquake, ground vibrations, and depends on natural period, of vibration and damping of the structure., , 3.22 Modes of Vibration ( see Normal Mode), , 3.31 Tectonic Features, , 3.23 Mode Shape Coefficient ( $i~), When a system is vibrating in normal mode k, at any, particular instant of time, the amplitude of mass, i expressed as a ratio of the amplitude of one of the, masses of the system, is known as mode shape, coefficient ( @i~)., , The nature of geological formation of the bedrock in, the earth’s crust revealing regions characterized by, structural features, such as dislocation, distortion,, faults, folding, thrusts, volcanoes with their age of, formation, which are directly involved in the earth, movement or quake resulting, in the above, consequences., , 3.24 Natural Period (T), , 3.32 Time History Analysis, , Natural period of a structure is its time period of, undamped free vibration., , It is an analysis of the dynamic respmse of the structure, at each increment of time, when its base is subjected, to a specific ground motion time history., , 3.24,1 Fundamental, , Natural, , Period ( T1), , 3.33 Zone Factor (Z), It is the first ( longest ) modal time period of vibration., , It is a factor to obtain the design spectrum depending, on the perceived maximum seismic risk characterized, by Maximum Considered Earthquake ( MCE ) in the, zone in which the structure is located. The basic zone, fiwtorsincluded in this standard are reasonable estimate, of effective peak ground acceleration., , 3.24.2 Modal Natural Period ( T~), The modal natural period of mode k is the time period, of vibration in mode k., 3.25 Normal Mode, , 3.34 Zero Period Acceleration ( ZPA ), , A system is said to be vibrating in a normal mode when, all its masses attain maximum values of displacements, and rotations simultaneously, and pass through, equilibrium positions simultaneously., , It is the value of acceleration response spectrum for, period below 0.03 s ( frequencies above 33 Hz)., -,., 4 TERMINOLOGY FOR EARTHQUAKE, ENGINEERING OF BUILDINGS, , 3.26 Response Reduction Factor (R), It is the factor by which the actual base shear force,, that would be generated if the structure were to remain, elastic during its response to the Design Basis, Earthquake ( DBE ) shaking, shall be reduced to obtain, the design lateral force., 3.27 Response, , 4.1 For the purpose of earthquake resistant design, ofbuildings in this standard, the following definitions, shall apply., 4.2 Base, It is the level at which inertia forces generated in the, strnctnre are transferred to the foundation, which then, transfers these forces to the ground., , Spectrum, , The representation, , of the maximum response of, 9

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IS 1893( Part 1 ) :2002, 4.3 Base Dimensions (d), , 4.14 Lateral Force Resisting Element, , Base dimension of the building along a direction is, the dimension at its base, in metre, along that direction., , It is part of the structural system assigned to resist, lateral forces., , 4.4 Centre of Mass, , 4.15 Moment-Resisting Frame, , The point through which the resultant of the masses, of a system acts. This point corresponds to the centre, of gravity of masses of system., , It is a frame in which members and joints are capable, of resisting forces primarily by flexure., 4.15.1 Ordinary, , 4.5 Centre of Stiffness, , Moment-Resisting, , Frame, , It is a moment-resisting frame not meeting special, detailing requirements for ductile behaviour., , The point through which the resultant of the restoring, forces of a system acts., , 4.15.2 Special Moment-Resisting, , Frame, , It is the value of eccentricity to be used at floor i in, torsion calculations for design., , It is a moment-resisting frame specially detailed, to provide ductile behaviour and comply with, the requirements given in IS 4326 or IS 13920 or, SP6(6)., , 4.7 Design Seismic Base Shear ( V~), , 4.16 Number of Storeys ( n ), , It is the total design lateral force at the base of a, structure., , Number of storeys of a building isthe number of levels, above the base. This excludes the basement storeys,, where basement walls are connected with the ground, floor deck or fitted between the building columns. But,, it includes the basement storeys, when they are not, so connected., , 4.6 Design Eccentricity, , ( e~i), , 4.8 Diaphragm, It is a horizontal, or nearly horizontal system, which, transmits lateral forces to the vertical resisting elements,, for example, reinforced concrete floors and horizontal, bracing systems., , 4.17 Principal Axes, Principal axes of a building are generally two mutually, perpendicular horizontal directions inphmof abuilding, along which the geometry of the building is oriented., , 4.9 Dual System, Buildings with dual system consist of shear walls, ( or braced frames ) and moment resisting frames such, that:, a), , The two systems are designed to resist the, total design lateral force in proportion to their, lateral stiffness considering the interaction, of the dual system at all floor levels; and, , b), , The moment resisting frames are designed, to independently resist at least 25 percent, of the design base shear., , 4.18 P-A Effect, It is the secondary effect on shears and moments of, frame members due to action of the vertical loads,, interacting with the lateral displacement of building, resulting from seismic for~es., 4.19 Shear Wall, It is a wall designed to resist lateral forces acting in, its own plane., 4.20 Soft Storey, , 4.10 Height of Floor ( hi ), , It is one in which the lateral stiffness is less than, 70 percent of that in the storey above or less than, 80 percent of the average lateral stiffness of the three, storeys above., , It is the difference in levels between the base of the, building and that of floor i., 4.11 Height of Structure(k), , 4.21 Static Eccentricity, , It is the difference in levels, in metres, between its, base and its highest level., , ( e~l), , It is the distance between centre of mass and centre, of rigidity of floor i., , 4.12 Horizontal Bracing System, It is a horizontal truss system that serves the same, function as a diaphragm., , 4.22 Storey, , 4.13 Joint, , 4.23 Storey Drift, , It is the portion of the column that is common to other, members, for example, beams, framing into it., , It is the displacement of one level relative to the other, level above or below., , It is the space between two adjacent floors., , 10

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IS 1893( Part 1 ) :2002, 4.24 Storey Shear ( ~), , n, , Number of storeys, , It is the sum of design lateral forces at all levels above, the storey under consideration., , N, , SPT value for soil, , Pk, , Modal participation factor of mode k, , Q,, , Lateral force at floor i, , Q~~, , Design lateral force at floor i in mode k, , r, , Number of modes to be considered as per, 7.8.4.2, , R, , Response reduction factor, , 4.25 Weak Storey, It is one in which the storey lateral strength is less, than 80 percent of that in the storey above, The storey, lateral strength is the total strength of all seismic force, resisting elements sharing the storey shear in the, considered direction., 5 SYMBOLS, , S’a/g Average response acceleration coefficient, , The symbols and notations given below apply to the, provisions of this standard:, .4h, , Design horizontal seismic coefficient, , A~, , Design horizontal acceleration spectrum, value for mode “kof vibration, , bi, , ith Floor plan dimension of the building, perpendicular to the direction of force, , c, , Index for the closely-spaced modes, , d, , Base dimension of the building, in metres,, in the direction in which the seismic force, is considered., , DL, , Response quantity due to dead load, , ‘dl, , Design eccentricity to be used at floor i, calculated as per 7.8.2, , e, , S1, , for rock or soil sites as given by Fig. 2, and Table 3 based on appropriate natural, periods and damping of the structure, , Static eccentricity at floor i defined as the, distance between centre of mass and centre, of rigidity, , T, , Undamped natural period of vibration of, the structure (in second ), , ~, , Approximate, seconds ), , Tk, , Undamped natural period of mode k of, vibration (in second ), , T1, , Fundamental natural period of vibration, (in second ), , VB, , Design seismic base shear, , pB, , Design base shear calculated using the, approximate fimdamental period T,, , q, , Peak storey shear force in storey i due to, all modes considered, , qk, , Shear force in storey i in mode k, , fundamental, , period ( in, , Response quantity due to earthquake load, for horizontal shaking along x-direction, , v roof Peak storey shear force at the roof due to, , ELY, , Response quantity due to earthquake load, for horizontal shaking along y-direction, , w, , Seismic weight of the structure, , Wi, , Seismic weight of floor i, , EL,, , Response quantity due to earthquake load, for vertical shaking along z-direction, , z, , Zone factor, , ELX, , all modes considered, , Oik, , Froof Design lateral forces at the roof due to all, , modes considered, Fi, , Design lateral forces at the floor i due to, all modes considered, , $?, , Acceleration due to gravity, , h, , Height of structure, in metres, , hi, , Height measured from the base of the, building to floor i, , I, , Importance factor, , IL, , Response quantity due to imposed load, , h4k, , Modal mass of mode k, , Mode shape coet%cient at floor i in mode, k, , 11, , a, , Peak response (for example member forces,, displacements, storey forces, storey shears, or base reactions ) due to all modes, considered, , %, , Absolute value of maximum response in, mode k, , kc, , Absolute value of maximum response in, mode c, where mode c is a closely-spaced, mode., , A*, , Peak response due to the closely-spaced, modes only

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IS 1893( Part 1 ) :2002, Pij, , oi, , for this difference in actual and design lateral loads., , Coefficient used in the Complete Quadratic, Combination ( CQC ) method while, combining responses of modes i andj, , Reinforced and prestressed concrete members shall, be suitably designed to ensure that premature failure, due to shear or bond does not occur, subject to the, provisions of IS 456 and IS 1343. Provisions for, appropriate ductile detailing of reinforced concrete, members are given in IS 13920,, , Circular frequency in rad/second in the, iti mode, , 6 GENERAL PRINCIPLES AND DESIGN, CRITERIA, , In steel structures, members and their connections, should be so proportioned that high ductility is obtain~, tide SP 6 ( Part 6 ), avoiding premature failure due to, elastic or inelastic buckling of any type., , 6.1 General Principles, 6.1.1 Ground, , Motion, , The characteristics ( intensity, duratio~ etc ) of seismic, ground vibrations expected at any location depends, upon the magnitude of earthquake, its depth of focus,, distance from the epicentre, characteristics of the path, through which the seismic waves travel, and the soil, strata on which the structure stands. The random, earthquake ground motions, which cause the structure, to vibrate, can be resolved in any three mutually, perpendicular directions. The predominant direction, of ground vibration is usually horizontal., , The specified earthquake loads are based upon postelastic energy dissipation in the structure and because, of this fact, the provision of this standard for design,, detailing and construction shall be satisfied even for, structures and members for which load combinations, that do not contain the earthquake effect indicate larger, demands than combinations including earthquake., 6.1.4 Soil-Structure, , Interaction, , The soil-structure interaction refers to the effects of, the supporting foundation medium on the motion of, structure. The soil-structure interaction may not be, considered in the seismic analysis for structures, supported on rock or rock-like material., , Earthquake-generated vertical inertia forces are to be, considered in design unless checked and proven by, specimen calculations to be not significant. Vertical, acceleration should be considered in structures with, large spans, those in which stability is a criterion for, design, or for overall stability analysis of structures., Reduction in gravity force due to vertical component, of ground motions can be particularly detrimental in, cases of prestressed horizontal members and of, cantilevered members. Hence, special attention should, be paid to the effect of vertical component of the ground, motion on prestressed or cantilevered beams, girders, and slabs., , 6.1.5 The design lateral force specified in this standard, shall be considered in each of the two orthogonal, horizontal directions of the structure. For structures, which have lateral force resisting elements in the two, orthogonal directions only, the design lateral force, shall be considered along one direction at a time, and, not in both directions simultaneously. Structures,, having lateral force resisting elements (for example, frames, shear walls ) in directions other than the two, orthogonal directions, shall be analysed considering, the load combinations specified in 6.3.2., , 6.1.2 The response of a structure to ground vibrations, is a fimction of the nature of foundation soil; materials,, form, size and mode of construction of structures;, and the duration and characteristics of ground motion., This standard specifies design forces for structures, standing on rocks or soils which do not settle, liquefi, or slide due to loss of strength during ground vibrations., , Where both horizontal and vertical seismic forces are, taken into account, load combinations specified, in 6.3.3 shall be considered., 6.1.6 Equipment and other systems, which are, supported at various floor levels of the structure, will, be subjected to motions corresponding to vibration, at their support points. In important cases, it may be, necessary to obtain floor response spectra for design, of equipment supports. For detail reference be made, to IS 1893 (Part 4)., , 6.1.3 The design approach adopted in this standard, is to ensure that structures possess at least a minimum, strength to withstand minor earthquakes ( <DBE ),, which occur frequently, without damage; resist, moderate earthquakes ( DBE ) without significant, structural damage though some non-structural damage, may OCCUE, and aims that structures withstand a major, earthquake ( MCE ) without collapse, Actual forces, that appear on structures during earthquakes are much, greater than the design forces speciiled in this standard., However, ductility, arising from inelastic material, behaviourand detailing, and overstrength, arising from, the additional reserve strength in structures over and, above the design strength, are relied upon to account, , 6.1.7 Additions, , to Existing Structures, , Additions shall be made to existing structures only, as follows:, a), , 12, , An addition that is structurally independent, from an existing structures shall be designed, and constructed in accordance with the, seismic requirements for new structures.

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IS 1893( Part 1 ): 2002, b), , these shall be combined as per 6.3.1.1 and 6.3.1.2, where the terms DL, IL and EL stand for the response, quantities due to dead load, imposed load and, designated earthquake load respectively., , An addition, that is not structurally, independent from an existing structure shall, be designed and constructed such that, the entire structure conforms to the seismic, force resistance requirements, for new, structures, unless the following three, conditions are complied with:, , 6.3.1.1, , 3), , for plastic, , design, , of steel, , In the plastic design of steel structures, the following, load combinations shall be accounted for:, , 1) The addition shall comply with the, requirements for new structures,, 2), , Load factors, , structures, , The addition shall not increase the seismic, forces in any structural elements of the, existing structure by more than 5 percent, unless the capacity of the element, subject to the increased force is still in, compliance with this standard, and, , 1), , 1.7( DL.+IL ), , 2), , 1.7( DL*EL), , 3), , 1.3( DL+lL*EL), , 6.3.1.2 Partial safety factors for limit state design, of reinforced concrete and prestressed, concrete, structures, , The additicn shall not decrease the, seismic resistance of any structural, element of the existing structure unless, reduced resistance is equal to or greater, than that required for new structures., , In the limit state design of reinforced and prestressed, concrete structures, the following load combinations, shall be accounted for:, , 6.1.8 Change in Occupancy, , 1), , 1.5( DL+lL), , When a change of occupancy results in a structure, being re-classified to a higher importance factor ( 1 ),, the structure shall conform to the seismic requirements, for anew structure with the higher importance factor., , 2), , 1.2( DL+ZL+EL), , 3), , 1.5( DL+EL), , 4), , 0.9DL* 1.5EL, , 6.2 Assumptions, , 6.3.2 Design Horizontal, , The following assumptions shall be made in the, earthquake resistant design of structures:, , When the lateral load resisting elements are, oriented along orthogonal horizontal direction, the, structure shall be designed for the effects due to till, design earthquake load in one horizontal direction at, time., , a), , 6.3.2.2 When the lateral load resisting elements are, not oriented along the orthogonal horizontal directions,, the stmcture shall be designed for the effects due to, foil design earthquake load in one horizontal direction, plus 30 percent of the design earthquake load in the, other direction., , NOTE — However, there are exceptions where, resonance-like conditions have been seen to occur, between long distance waves and tall structures, founded on deep soft soils., , Earthquake, is not likely to occur, simultaneously with wind or maximum flood, or maximum sea waves,, , c), , The value of elastic modulus of materials,, wherever required, may be taken as for static, analysis unless a more definite value is, available for use in such condition ( see, IS 456, IS 1343 and IS 800 ), , Load, , 6.3.2.1, , Earthquake causes impulsive ground motions,, which are complex and irregular in character,, changing in period and amplitude each lasting, for a small duration. Therefore, resonance of, the type as visualized under steady-state, sinusoidal excitations, will not occur as it, would need time to buildup such amplitudes., , b), , Earthquake, , NOTE — For instance, the building should be designed, for ( + ELx i 0.3 EL.y ) as well as ( * 0.3 ELx * ELy ),, where x and y are two orthogonal horizontal directions,, EL in 6.3.1.1 and 6.3.1,2 shall be replaced by ( ELx i, 0.3 ELy ) or ( ELy i 0.3 .!Lh )., , 6.3.3 Design Vertical Earthquake, , Load, , When effects due to vertical earthquake loads are to, be considered, the design vertical force shall be, calculated in accordance with 6.4.5., 6.3.4, , Combination, , for Two or Three Component, , 6.3 Load Combination and Increase in Permissible, Stresses, , Motion, , 6.3.1 Load Combinations, , When responses from the three earthquake, components are to be considered, the responses due, to each component may be combined using the, 6.3.4.1, , When earthquake forces are considered on a structure,, 13

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IS 1893( Part 1 ) :2002, Zones III, IV, V and less than 10 in seismic Zone II,, the vibration caused by earthquake may cause, liquefaction or excessive total and differential, settlements. Such sites should preferably be avoided, while locating new settlements or important projects., Otherwise, this aspect of the problem needs to be, investigated and appropriate methods of compaction, or stabilization adopted to achieve suitable N-values, as indicated in Note 3 under Table 1. Alternatively,, deep pile foundation may be provided and taken to, depths well into the layer which is not likely to liquefi., Marine clays and other sensitive clays are also known, to lique~ due to collapse of soil structure and will, need special treatment according to site condition., , assumption that when the maximum response from, one component occurs, the responses from the other, two component are 30 percent of their maximum. All, possible combinations of the three components ( ELx,, ELy and ELz ) including variations in sign ( plus or, minus ) shall be considered, Thus, the response due, earthquake force (EL ) is the maximum of the following, three cases:, 1) %ELX*O.3 ELyho.3ELz, 2) *ELy*O.3 ELx&O.3 ELz, 3), , *ELz*, , 0.3 ELx&O.3 ELy, , where x and y are two orthogonal directions and z is, vertical direction., , NOTE — Specialist literature may be referred, determining liquefaction potential of a site., , 6.3.4.2 As an alternative to the procedure in 6.3.4.1,, the response (EL ) due to the combined effect of the, three components can be obtained on the basis of, ‘square root of the sum of the square ( SRS S )‘ that, is, EL = ~ (ELx)2+, , 6.4, , Design Spectrum, , 6.4.1 For the purpose of determining seismic forces,, the country is classified into four seismic zones as, shown in Fig. 1., , (ELy)z+(ELz)2, , 6.4.2 The design horizontal seismic coefficient Ah, for a structure shall be determined by the following, expression:, , NOTE — The combination procedure of 6.3.4.1 and, 6.3.4.2 apply to the same response quantity (say, moment, in a column about its major axis, or storey shear in a, frame) due to different components of the ground motion., , .zIsa, Ah=—, , 6.3.4.3 When two component motions ( say one, , 2Rg, , horizontal and one vertical, or only two horizontal), are combined, the equations in 6.3.4.1 and 6.3.4.2, should be modified by del >ting the term representing, the response due to the component of motion not being, considered., 6.3.5 Increase in Permissible, , for, , Provided that for any structure with T <0.1 s, the, value of A~will not be taken less than Z/2 whatever, be the value of I/R, where, , Stresses, , z., , When earthquake forces are considered along with, other normal design forces, the permissible stresses, in material, in the elastic method of design, maybe, increased by one-third. However, for steels having a, definite yield stress, the stress be limited to the yield, stress; for steels without a definite yield point, the, stress will be limited to 80 percent of the ultimate, strength or 0.2 percent proof stress, whichever is, smaller; and that in prestressed concrete members,, the tensile stre’ssin the extreme fibers of the concrete, may be permitted so as not to exceed two-thirds of, the modulus of rupture of concrete., , Zone factor given in Table 2, is for the, Maximum Considered Earthquake ( MCE ), and service life of structure in a zone. The, factor 2 in the denominator of Z is used so, as to reduce the Maximum Considered, Earthquake ( MCE ) zone factor to the fktor, for Design Basis Earthquake ( DBE )., , z=, , Importance factor, depending upon the, functional, use of the structures,, characterised by.hazardous consequences, of its failure, post-earthquake functional, needs, historical value, or economic, importance ( Table 6 )., , 6.3.5.2 Increase, , R=, , Response reduction factor, depending on, the perceived seismic damage performance, of the structure, characterised by ductile, or brittle deformations. However, the ratio, (I/R ) shall not be greater than 1.0( Table, 7). The values of R for buildings are given, in Table 7., , 6.3.5.1, , Increase impermissible, , in allowable, , stresses in materials, , pressure, , in soils, , When earthquake forces are included, the allowable, bearing pressure in soils shall be increased as per, Table 1, depending upon type of foundation of the, structure and the type of soil., In soil deposits consisting of submerged loose sands, and soils falling under classification, SP with, standard penetration N-values less than 15 in seismic, , S’a/g = Average response acceleration coefficient, 14

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IS 1893( Part 1 ): 2002, Table 1 Percentage of Permissible Increase in Allowable Bearing Pressure or Resistance of Soils, (L’lause 6.3.5.2), Foundation, , S1 No., , Type of Soil Mainly Constituting, the, A, r, Type I Rock or Hard Soil : Type H Medium S&ls :, Well graded gravel and sand All soils with N between 10, gravel mixtures with or and 30, and poorly graded, without clay binder, and sands or gravelly sands with, clayey sands poorly graded little or no fines ( SP1~), or sand clay mixtures ( GB, with N> 15, CW, SB, SW, and SC )1), having )@ above 30, where, N is the standard penetration, value, , Foundation, >, Type III Soft Soils: AU, soils other than SP’J, with N< 10, , (1), , (2), , (3), , (4), , (5), , 1), , Piles passing through any, soil but resting on soil type I, , 50, , 50, , 50, , ii), , Piles not covered, item i, , 25, , 25, , iii), , Raft foundations, , 50, , 50, , 50, , iv), , Combined isolated RCC, footing with tie beams, , 50, , 25, , 25, , v), , Isolated RCC footing without, tie beams, or unreinforced, strip foundations, , 50, , 25, , —, , vi), , Well foundations, , 50, , 25, , 25, , under, , NOTES, 1 The allowable bearing pressure shall be determined in accordance with IS 6403 or IS 1888., 2 If any increase in bearing pressure has already been permitted for forces other than seismic forces, the total increase, in allowable bearing pressure when seismic force is also included shall not exceed the limits specified above., 3 Desirable minimum field values of N — If soils of smaller N-values are met, compacting may be adopted to achieve, these values or deep pile foundations going to stronger strata should be used., 4 The values of N ( corrected values ) are at the founding level and the allowable bearing pressure shall be determined in, accordance with IS 6403 or IS 1888., ,, Seismic Zone, Depth Below Ground, N-Values, Remark, level (in metres ), III, IV and V, , 11 ( for important, structures only ), , <5, , 15, , > lo, , 25, , <5, > Ir), , 20, , 15, , For values of depths between 5 m and, 10 m, linear, interpolation, is, recommended, , 5 The piles should be designed for lateral loads neglecting lateral resistance of soil layers liable to liquefy., 6 IS 1498 and IS 2131 may also be referred., 7 Isolated R, C.C. footing without tie beams, or unreinforced strip foundation shall not be permitted in soft soils with, N<1O., 1) See IS 1498., 2), , See IS 2131., , 15

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IS-1893 ( Part 1 ) :2002, for rock or soil sites as given by Fig. 2 and, Table 3 based on appropriate natural periods, and damping of the structure. These curves, represent free tleld ground motion., , foundations placed between the ground level and, 30 m depth, the design horizontal acceleration spectrum, value shall be linearly interpolated between Ah and, 0.5 Ah, where Ah is as specified in 6.4.2., , NOTE — For various types of structures, the, values of Importance Factor I, Response Reduction, Factor R, and damping values are given in the, respective parts of this standard. The method, ( empirical or otherwise ) to calculate the natural, periods of the structure to be adopted for evaluating, S,/g is sdso given in the respective parts of this, standard., , 6.4.5 The design acceleration spectrum for vertical, motions, when required, may be taken as two-thirds, of the design horizontal acceleration spectrum specitled, in 6.4.2., Figure 2 shows the proposed 5 percent spectra for, rocky and soils sites and Table 3 gives the multiplying, factors for obtaining spectral values for various other, clampings., , Table 2 Zone Factor, Z, ( Clause 6.4.2), Seismic, Zone, , II, , Seismic, Intensity, , Low, , 0.10, , z, , For rocky, or hard soil sites, , Iv, , v, , Moderate, , Severe, , Very, Severe, , 0.16, , 0,24, , 0.36, , 111, , s,, g, -1, , r, , 2.50, , O.1O<T<O.4O, , l.00/T, , 0.40< TS4.00, , 1+15~, , O.OO<TSO.1O, , 2.50, , O.1O<T<O.55, , I 1.361T, , 0.55 sT<4.00, , s, ~, g, , =, , For soft soil sites, , 6.4.4 For underground structures and foundations, at depths of 30 m or below, the design horizontal, acceleration spectrum value shall be taken as half the, value obtained from 6.4.2. For structures and, , 1, , 0.00< Ts”o.lo, , For medium soil sites, , 6.4.3 Where a number of modes are to be considered, for dynamic analysis, the value of Ah as defined, in 6.4.2 for each mode shall be determined using the, natural period of vibration of that mode., , 3.0, , =, , 1+15~, , 1+15Z, , Sa, =, , T, , r, , r, , I, , 0.00 S T<O.1O, , 2.50, , 0.10 S TsO.67, , 1 1.67/T, , 0.67 ST<4.00, , ,, , ,, , Type 1 (Rock, or Hard So, 2.5, T, , .....‘,, ‘, ,., ‘! ,,, \ ‘., , Type II (Medium Soil), h, , /Tv~e II1(Soft Soil), , 2.0, , 1.5, , 1.0, , 0.5, , —, , -----------, , --.--.--:.. ........, ---------—, , 0.0, 0.0, , 0.5, , 1.0, , 1“5, , 2’0, , 2“5, , 3“0, , 3“5, , Period(s), , Fm., , 2 RESPONSE, SPECTRA, ~R ROCKANDSOILSITESFOR5 PERC~ DAMPM, 16, , 4“0

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IS 1893( Part 1 ): 2002, and 6.3.1.2 where the gravity loads are combined with, the earthquake loads [ that is, in load combinations, (3) in 6.3.1.1, and (2) in 6.3.1.2 ]. No further reduction, in the imposed load will be used as envisaged in, IS 875( Part 2 ) for number of storeys above the one, under consideration or for large spans of beams or, floors., , 6.4.6 In case design spectrum is specifically prepared, for a structure at a particular project site, the same, may be used for design at the discretion of the project, authorities, , 7 BUILDINGS, 7.1 Regular and Irregular, , Configuration, , 7.3.4 The proportions of imposed load indicated above, for calculating the lateral design forces for earthquakes, are applicable to average conditions. Where the, probable loads at the time of earthquake are more, accurately assessed, the designer may alter the, proportions indicated or even replace the entire, imposed load proportions by the actual assessed load., In such cases, where the imposed load is not assessed, as per 7.3.1 and 7.3.2 only that part of imposed load,, which possesses mass, shall be considered. Lateral, design force for earthquakes shall not be calculated, on contribution of impact effects from imposed loads., , To perform well in an earthquake, a building should, possess four main attributes, namely simple and regular, cotilguration, and adequate lateral strength, stiffness, and ductility. Buildings having simple regolar geomet~, and uniformly distributed mass and stiffness in plan, as well as in elevation, suffer much less damage than, buildings with irregular configurations. A building, shall be considered as irregular for the purposes of, this standard, if at least one of the conditions given, in Tables 4 and 5 is applicable,, 7.2 Importance, FactorR, , Factor Zand Response Reduction, , 7.3.5 Other loads apart from those given above ( for, example snow and permanent equipment ) shall be, considered as appropriate., , The minimum value of importanm factor,1, for ditlerent, building systems shall be as given in Table 6. The, response reduction factor, R, for different building, systems shall be as given in Table 7., , 7.4 Seismic Weight, 7.4.1 Seismic, , 7.3 Design Imposed Loads for Earthquakes Force, Calculation, , Weight of Floors, , The seismic weight of each floor is its full dead load, plus appropriate amount of imposed load, as specified, in 7.3.1 and 7.3.2. While computing the seismic weight, of each floor, the weight of columns and walls in any, storey shall be equally distributed to the floors above, and below the storey., , loading classes as specified in, 7.3.1 For various, IS 875( Part 2 ), the earthquake force shall be calculatcxl, for the full dead load plus the percentage of imposed, load as given in Table 8., , 7.4.2 Seismic Weight of Building, , 7.3.2 For calculating the design seismic forces of the, structure, the imposed load on roof need not be, considered., , The seismic, , 7.3.3 The percentage of imposed loads given in 7.3.1, and 7.3.2 shall also be used for ‘Whole frame loaded’, condition in the load combinations specified in 6.3. L 1, , 7.4.3 Any weight supported in between storeys shall, be distributed to the floors above and below in inverse, proportion to its distance from the floors., , weight, , of the whole building, , is the sum, , of the seismic weights of all the floors., , Table 3 Multiplying Factors for Obtaining Values for Other Damping, ( Clause 6.4.2), Damping,, percent, Factors, , o, , 2, , 5, , 7, , 10, , 15, , 20, , 25, , 30, , 3.20, , 1,40, , 1.00, , 0.90, , 0.80, , 0.70, , 0,60, , 0.55, , 0.50, , 17

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IS 1893( Part 1 ) :2002, Table 5 — Concluded, , Table 4 Definitions of Irregular Buildings —, Plan Irregularities ( Fig. 3 ), , Irregularity, , S1 No., , ( Clause 7.1 ), , Type and Description, (2), , (1), S1 No., , Irregularity, , Type and Description, , i), , ii), , (2), , (1), , Mass irregularity shall be considered to exist where, the seismic weight of any storey is more than 200, percent of that of its adjacent storeys. The irregularity, need not be considered in case of roofs, , Torsion Irregularity, To be considered when floor diaphragms are rigid, in their own plan in relation to the vertical structural, elements that resist the lateral forces. Torsional, irregularity to be considered to exist when the, maximum storey drift, computed with design, eccentricity, at one end of the structures transverse, to an axis is more than 1.2 times the average of, the storey drifts at the two ends of the structure, , ii), , Vertical Geometric Irregularity, , iii), , Vertical geometric irregularity shall be considered, to exist where the horizontal dimension of the lateral, force resisting system in any storey is more than, 150 percent of that in its adjacent storey, , Re-en?rant Corners, , iv), , Plan configurations of a structure and its lateral, force resisting system contain re-entrant corners,, where both projections of the structure beyond the, re-entrant corner are greater than 15 percent of, its plan dimension in the given direction, iii), , Mass Irregulari@, , In-Plane Discontinuity in VerticalElenrentsResisttng, Lateral Force, A in-plane offset of the lateral force resisting, elements greater than the length of those elements, Discontinuity in CapaciQ — Weak Strorey, , v), , A weak storey is one in which the storey lateral, strength is less than 80 percent of that in the storey, above, The storey lateral strength is the total, strength of all seismic force resisting elements, sharing the storey shear in the considered direction., , Diaphragm Discontinuity, Diaphragms with abrupt discontinuities or variations, in stiffness, including those having cut-out or open, areas greater than 50 percent of the gross enclosed, diaphragm area, or changes in effective diaphragm, stiffness of more than 50 percent from one storey, to the next, , iv), , Table 6 Importance Factors, 1, , Out-of-Plane Offsets, , ( Clause 6.4.2), , Discontinuities in a lateral force resistance path,, such as out-of-plane offsets of vertical elements, v), , S1 No., , Strue tur e, , (1), , (2), , i), , Important service and community, buildings, such as hospitals; schools;, monumental structures; emergency, buildings like telephone exchange,, television stations, radio stations,, railway stations, fire station buildings;, large community halls like cinemas,, assembly halls and subway stations,, power stations, , Non-parallel Systems, The vertical elements resisting the lateral force, are not parallel to or symmetric about the major, orthogonal axes or the lateral force resisting elements, , Table 5 Definition of Irregular Buildings —, Vertical Irregularities ( Fig. 4 ), ( Clause 7.1 ), S1 No., (1), i), , Irregularity, , Type and Description, (2), , ii), , a) Stiffness Irregularity — Soft Storey, , AU other buildings, , Importance, Factor, (3), , 1.5, , 1.0, , NOTES, , A soft storey is one in which the lateral stiffness, is less than 70 percent of that in the storey above, or less than 80 percent of the average lateral stiffness, of the three storeys above, , 1 The design engineer may choose values of importance, factor I greater than those mentioned above., 2 Buildings not covered in SI No. (i) and (ii) above may, be designed for higher value ofZ, depending on economy,, strategy considerations like multi-storey buildings having, several residential units., , b) Stiffness Irregularity — Extreme Soft Storey, A extreme soft storey is one in which the lateral, stiffness is less than 60 percent of that in the storey, above or less than 70 percent of the average stiffness, of the three storeys above. For example, buildings, on STILTS will fall under this category,, , 3 This does not apply to temporary structures, excavations, scaffolding etc of short duration., , 18, , like

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IS 1893 (Part 1 ): 2002, , I, , \, , I, \, , i,, , /, \l, , i, , ., , VERTICAL, COMPONENTS, OF, SEISMIC, RESISTING, SYSTEM, , —-——, , --, , —.., , —.——, , FLOOR, i, i, I, , Al, J_, , I, , Az, , +-----------+f, 3 ATorsional Irregularity, , -r, , I, , A\ L> O-15-0,20, , IL-r, , L, , ‘7, , 7, , L2, , A2, , Al, , 3 B Re-entrant Corner, FIG. 3 PLAN IRREGULARITIES, — Continued, , 19

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IS 1893( Part 1 ) :2002, MASS, , RESISTANCE, , ECCENTRICITY, , m“m, VERTICAL, , COMPONENTS, OF, SYSTEM, , E, , SEISMIC, , RESISTING, , OPENING, , FLOOR, , 3 C Diaphragm Discontinuity, , +--SHEAR, WALL, , /////////, , ///,’//, , BUILDING, , o, D, , ///////, , SECTION, , WALLS, , 3 D Out-of-Plane Offsets, , EE3, BUILDING, , PLAN, , 3 E Non-Parallel System, FIG. 3 PLAN IRREGULARITIES, , 20

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IS 1893( Part 1 ): 2002, , Q&j, A, , A, , AIL>O-10, , AIL >0-15, , ALA, , b, , 4 C Vertical Geometric Iregularity, , when L2 >1.5 L,, , STOREY STRENGTH, (LATERAL), Fn, , B., , Fn.l, , Fn.2, , ., 4 E weak Storey when ~ c 0,8 ~ + 1, , 4 D In-Plane Discontinuity in Vertical Elements Resisting, Lateral Force when b > a, , FIG.4 VEKHCALIRREGULAIUHSS, , 22

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IS 1893( Part 1 ): 2002, Table 7 Response Reduction Factor l), R, for Building Systems, , ., , ( Clause 6.4.2), Lateral, , S1 No., , Load Resisting, , R, , System, , (3), , (2), , (1), Building Frame Systems, i), , 4, , Ordinary RC moment-resisting, , ii), , Special RC moment-resisting, , iii), , Steel frame with, , iv), , 3.0, , frame ( OMRF )2), , 5.0, , frame ( SMRF )3), ., , a) Concentric braces, , 4.0, , b) Eccentric braces, , 5.0, 5.0, , Steel moment resisting frame designed as per SP 6 ( 6 ), Building with Shear Walls4~, , v), , Load bearing masonry wall buildings), a) Unreinforced, , 1.5, , b) Reinforced with horizontal RC bands, , 2.5, , c) Reinforced with horizontal RC bands and vertical bars at corners of rooms and, jambs of openings, , 3.0, , vi), , Ordinary reinforced concrete shear walls@, , 3.0, , vii), , Ductile shear walls7), , 4.0”, , Buildings with Dual Systemss), viii), , Ordinary shear wall with OMRF, , 3.0, , ix), , Ordinary shear wall with SMRF, , 4,0, , x), , Ductile shear wall with OMRF, , 4.5, , xi), , Ductile shear wall with SMRF, , 5.0, , 0 The va]ues of response riduction fact&s are to be used for buildings with lateral load resisting elements, and not Just, for the lateral load resisting elements built in isolation., 2) OMRF, , are those designed, , and, , detailedas per IS 456 or Is 800” but not, , meeting, , ductile detailing, , reqllirertlellt, M, , per IS 13920 or SP 6 (6) respectively., b, , 3), , SMRF defined in 4.15.2., , 4) Buildings, , with shear walls also include buildings having shear walls and frames, but where:, , a) frames are not designed to carry lateral loads, or, b) frames are designed to carry lateral loads but do not fulfil the requirements of ‘dual systems’., 5), , Reinforcement, , 6), , Prohibited in zones IV and V., , n, , Ductile shear walls are those designed and detailed as per IS 13920., , s), , Buildings with dual systems consist of shear walls ( or braced frames ) and moment resisting frames such that:, , should be as per IS 4326., , a) the two systems are designed to resist the total design force in proportion to their lateral stiffness considering, the interaction of the dual system at all floor levels,; and, b) the moment resisting frames are designed to independently resist at least 25 percent of the design seismic base, shear,, , .23, , ,,, , ,

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IS 1893( Part 1 ): 2002, 7.6.2 The approximate fundamental natural period, of vibration ( T, ), in seconds, of all other buildings,, including moment-resisting fimne buildings with brick, intil panels, may be estimated by the empirical, expression:, , Table 8 Percentage of Imposed Load to be, Considered in Seismic Weight Calculation, 7.3.1 ), , (Clause, Imposed Uniformity, Distributed Floor, Loads ( kN/ mz ), , Percentage, , of Imposed, Load, , 0.09, ‘=, , (1), , (2), , Upto and including 3.0, , 25, , Above 3.0, , 50, , m, , where, h=, , Height ofbuilding, inw as defined in7.6.l;, and, , d=, , 7.5 Design Lateral Force, , 7.5.1 Buildings and portionsthereof shall be designed, and constructed, to resist the effects of design lateral, force specified in 7.5.3 as a minimum., , Base dimension of the building at the plinth, level, in m, along the considered direction, of the lateral force., ., , 7.7 Distribution, , of Design Force, , 7.7.1 Vertical Distribution, Floor LeveLr, , 7.5.2 The design lateral force shall first be computed, for the building as a whole. This design lateral force, shall then be distributed to the various floor levels., The overall design seismic force thus obtained at each, floor level, shall thenbe distributed to individual lateral, load resisting elements depending on the floor, diaphragm action., , of Base Shear to Differmt, , The design base shear ( V~ ) computed in 7.5.3 shall, be distributed along the height of the building as per, the following expression:, W h,z, , l’, , Qi=J’B., , 7.5.3 Design Seismic Base Shear, where, , The total design lateral force or design seismic base, shear ( VB) along any principal direction shall, be determined by the following expression:, , Qi = Design lateral force at floor i,, Wi = Seismic weight of floor i,, , V~ = AhW, , hi = Height of floor i measured from base, and, , where, n, , Ah = Design horizontal acceleration spectrum, value as per 6.4.2, using the fundamental, natural period T,as per 7.6 in the considered, direction of vibration, and, , ., , Number of storeys in the building is the, number of levels at which the masses are, located., , 7.7.2 Distribution of Horizontal Design Lateral Force, to Different Lateral Force Resisting, , w., , Seismic weight of the building as per 7.4.2., , 7.6.1 The approximate fundamental natural period, of vibration ( T, ), in seconds, of a moment-resisting, frame building without brick in.fd panels may be, estimated by the empirical expression:, , = 0.085 h075, , 7.7.2.2 In case of building whose floor diaphragms, can not be treated as infinitely rigid in their own plane,, the lateral shear at each floor shall be distributed to, the vertical elements resisting the lateral forces,, considering the in-plane flexibility of the diaphragms., , for RC frame building, for steel frame building, , where, h, , =, , Elements, , 7.7.2.1 In case of buildings whose floors are capable, of providing rigid horizontal diaphragm action, the, total shear in any horizontal plane shall be distributed, to the various vertieal elements of lateral force resisting, system, assuming the floors to be infinitely rigid in, the horizontal plane., , 7.6 Fundamental Natural Period, , T. = 0,075 h07s, , *, , Height of building, in m. This excludes, the basement storeys, where basement walls, are connected with the ground floor deck, or fitted between the building columns., But it includes the basement storeys, when, they are not so connected., , NOTES, 1 A floor diaphragm shaJl be considered to be flexible,, if it deforms such that the maximum lateral displacement, measured from the chord of the deformed shape at, any point of the diaphragm is more than 1.5 times the, average displacement of the entire diaphragm., 24, , .

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IS 1893( Part 1 ): 2002, building shall be petiormed as per established methods, of mechanics using the appropriatemasses and elastic, stiffness of the structural system, to obtain natural, periods (T) and mode shapes {$} of those of its modes, of vibration that need to be considered as per 7.8.4.2., , 2 Reinforced concrete monolithic slab-beam floors or, those consisting of prefabricated/precast elements with, topping reinforced screed can be taken a rigid diaphragms., , 7.8 Dynamic Analysis, 7.8.1 Dynamic analysis shall be pefiormed to obtain, the design seismic force, andits distributionto different, levels along the height of the building andtothevarious, lateral load resisting elements, for the following, buildings:, , 7.8.4.2 Modes to be considered, The number of modes to be used in the analysis should, be such that the sum total of modal masses of all modes, considered is at least 90 percent of the total seismic, mass and missing mass correction beyond 33 percent., If modes with natural frequency beyond33 Hz are to, be considered, modal combination shall be carried out, only for modes upto 33 Hz. The effect of higher modes, shall be included by considering missing mass, correction following well established procedures., , a) Regular buildings — Those greater than, 40 m in height in Zones IV and ~ and those, greater than 90 m in height in Zones II and, 111. Modelling as per 7.8.4.5 can be used., b) irregular buildings ( as defined in 7.1 ) —, Allfiamedbuildingshigherthan12minZones, IVand~andthosegreaterthan40minheight, in Zones 11and III., , 7.8.4.3 Analysis, , of building, , subjected, , to design, , forces, , The analyticalmo&l fordynamicanalysisof buildings, with unusual configuration should be such that it, adequately models the types of irregularities present, in the building configuration. Buildings with plan, irregularities,as defimedin Table4 ( as per 7.1 ), cannot, be modelled for dynamic analysis by the method given, in 7.8.4.5., , The building may be analyzed by accepted principles, of mechanics for the design forces considered as static, forces., 7.8.4.4 Modal combination, The peak response quantities ( for example, member, forces, displacements, storey forces, storey shears, and base reactions ) shall be combined as per Complete, Quadratic Combination ( CQC ) method., , NOTE — For irregular buildings, lesser than 40 m in, height in Zones 11and III, dynamic anrdysis, even though, not mandatory, is recommended., 7.8.2, , Dynamic, , by the, , Time, , Spectrum, , analysis, History, , Method., , may be performed, , Method, However,, , in either, , design base shear ( VB) shall be compared, shmr ( J?B) calculated using a fundamental, where, , either, , I, , or by the Response, method,, , ,,, , the, , with abase, period T,,, , where, , T, is as per 7.6. Where t’~is less than ~~, all, , the response quantities (for example member forces,, displacements, storey forces, storey shears and base, reactions) shall be multiplied by ~~ / V~., , r, , . Number of modes being considered,, , pij, , =, , Cross-modal coeffkient,, , 7.8.2.1 The value of damping for buildings maybe, takenas 2 and 5 percentof the critical, forthe purposes, of dynamic analysis of steel and reinforced concrete, buildings, respectively., , Ai, , =, , Response quantity in mode i ( including, sign ),, , Lj = Response quantity in mode j ( including, sign ),, , 7.8.3 Time History Method, , 8&(l+J3)~15, , Time history method of analysis, when used, shall, be based on an appropriate ground motion and shall, be performed using accepted principles of dynamics., ‘7.8.4 Response, , pij, , (l+p2)2+452p(, , 7.8.4.1 Free Ebration, , Analysis, , free vibration, , l+/.3)2, , ~=, , Modal damping ratio (in ffaction) as, specified in 7.8.2.1,, , p=, , Frequency ratio = O,/(oi,, , 0.),=, , Circular frequeney in ith mode, and, , (l)j=, , Circular frequeney injth mode., , Spectrum Method, , Response spectrum method of analysis shall be, performed using the design spectrum specified in 6.4.2,, or by a site-specific design spectrum mentioned, in 6.4.6., , Undamped, , =, , Alternatively, the peak response quantities may be, combined as follows:, , analysis of the entire, 25, , .’

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IS 1893 (, a), , Part 1 ) : 20{)2, , If the building, modes,, , then, , c), , does not have closely-spaced, the, , ( k ) due to all, , peak, , response, , quantity, , modes considered shall be, , obtained as, , Design Lateral Force at Each Floor in Each, Mode — The peak lateral force ( Qi~) at floor, i in mode k is given by, , Q,k = .4k ~,~‘k ‘,, where, .4k = Design’ horizontal, acceleration, spectrum value as per 6.4.’2 using, the natural period of vibration ( Tk), of mode k., , k~ = Absolute value of quantity in mode k, and, r, b), , d) Storey Shear Forcev in Each Mode — The, peak shear force ( P’,k) acting in storey i in, mode k is given by, , = Number of modes being considered, If the building has a few closely-spaced modes, ( see 3.2), then the peak response quantity, ( k“ ) due to these modes shall be obtained, as, , &, j=l+l, , e), , f), , ~orces, , at Each, , Con,videred, , Storey, , Due, , to .411, , —, , F,,,,,f = I;,,(,f, and, * [/;– J.:+,, , F,, , 7.9 Torsion, .!, , 7.9.1 Provision shall be made jn all buildings for., increase in shear forces on.the lateral force resisting, elements resulting from the horizontal torsional moment, arising due to eccentricity between the centre of mass, and centre of rigidity. The design forces calculated, as in 7,8.4.5 are to be applied at the centre of nl~s, appropriately displaced so as to cause design, eccentricity ( 7.9.2 ) between the displaced centre of,, mass and centre of rigidity. However, negative torsional, shear shall be neglected., , The mockdmass ( M~) of mode, , ●, , 7.9.2 The design eccentricity, e~ito, -. be used at floor, , where, , i shall be taken as:, , = Acceleration due to gravity,, , 1.5e,, + 0,05 b,, , $i~ = Mode shape coefficient at floor J in, mode k, and, , ‘dl, , =, , ,1, , or, , e,i –, , 0.05 bi, , whichever of these gives the more severe effect n, the shear of any ’frame where, , Py = Seismic weight of floor i., b), , Lateral, , The design lateral, forces, F,,,,,f and F,, at roof and at floor i :, , k is given by, , ~, , Shear Forcetv due to .411 A40dev, C’onividered — The peak storey shear force, , Mode,v, , 7.8.4.5 Buildings with regular, or nominally irregyla~{, plan configurations may be modelled as a system of, nm.ses lumped at the floor levels with each mass having, one degree of freedom, that of lateral displacement, in the direction under consideration. In such a case;, the following expressions shall hold in the computation, of the various quantities : “, A40dalA4ass —, , Storey, , ( Vi) in storey i due to all modes considered, is obtained by combining those due to each, mode in accordarice with 7:8.4.4., , where the summation is for the closely-spaced modes, only This peak response quantity due to the closely, spaced modes ( L“ ) is then combined with those of, the remaining well-separated modes by the method, described in 7.8.4.4 (a)., , a), , ,, , Participation, Factors, — The, modal participation factor ( P~ ) of mode k is, given by:, , Modal, , ‘dl =, , Static eccentricity at floor i defined as the, distance between centre of mass and centre, of rigidity, and, , b,, , Floor plan dimension, of floor i,, perpendicular to the direction of force., , n, , x, , ‘, @,k, , =, , NOTE — The, , factor 1.5 represents, dynamic, amplification factor, while the factor 0,05 represents, the extent of accidental eccentricity., , ,=1, , 26, , .

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IS 1893( Part 1 ) :2002, direction under consideration, do not lose their vertical, load-carrying capacity under the induced moments, resulting from storey deformations equal to R times, the storey displacements calculated as per 7.11.1., where R is specified in Table 7., , 7.9.3 In case of highly irregular buildings analyzed, to 7.8.4”.5, additive shears will be, according, superimposed for a statically applied eccentricity of, + ().()5b, with respect to the centre of rigidity, , Buildings with Soft Storey, , 7.10, 7.10.1, , In case buildings, , as the ground, , storey, , with a flexible, , consisting, , parking that is Stilt buildings,, to be made to increase, of the soft/open, , of open spaces, , special arrangement, , the lateral strength, , NOTE — For instauce, cnnsider a flat-slab building in, which lateral Inad resistance is provided by shear walls., Since the Isstersdload resistance rfthe slab-column system, is small. these are nften designed nnly for the gravity, loads, while all the seismic force is resisted by the shear, walls. Even thnugh the slabs and columns are not required, to share the lateral forces, these det-orm with rest ot’, the structure. under seismic force, The concern is tbtit, under such detbrmations, the slab-column system should, not lose its vertical Iuad capucity., , storey, such, for, , needs, , and stiffness, , storey., , 7.10.2 Dynamic analysis of building is carried out, including the strength and stiffness effects of infills, and inelastic deformations in the members, particularly,, those in the soft storey, and the members designed, accordingly,, , 7.10.3 Alternatively,, to be adopted, , after, , the following, carrying, , 7.11.3 Separation, same building, , design criteria are, , 7.11, , with separatiolljoint, , in between, , shall, , times, the sum of the calculated storey displacements as per, 7.11.1 of each of them, to avoid damaging con~act, when the two units deflect towards each other. When, floor levels of two similar adjacent units or buildings, are at the same elevation levels, factor R in this, requirement may be replaced by R/2., , out the earthquake, , 7.12 Miscellaneous, , besides the columns designed and detailed, for the calculated storey shears and moments,, shear walls placed symmetrically in both, directions of the building as far away from, the centre of the building as feasible; to be, designed exclusively for 1.5 times the lateral, storey shear force calculated as before,, , 7.12.1, , Foundations, , The use of foundations vulnerable to significant, differential settlement due to ground shaking shall, be avoided for structures in seismic Zones III, IV and, V In seismic Zones IV and V,individual spread footings, or pile caps shall be interconnected, with ties,, ( .~ee5.3.4.1 of 1S4326 ) except when individual spread, footings are directly supported on rock. All ties shall, be capable of carrying, in tension and in compression,, an axial force equal to .4, /4 times the larger of the, , Deformations, , 7.11.1, , [Jnits, , be separated by a distance equal to the amount R, , the columns and beams of the soft storey are, to be designed for 2.5 times the storey shears, and moments calculated under seismic loads, specified in the other relevant clauses: or., , b), , .4djacent, , Two adjacent buildings. or two adjacent units of the, , analysis, neglecting the effect of infill walls in other, storeys:, a), , Between, , Store,v Drift Limitation, , ,1, , The storey, specified, , drift, design, , in any storey, lateral, , column, , due to the minimum, , force, with partial, , computed, , load factor, , or pile cap load, in addition, forces,, , of 1,(). shall not exceed O.()()4 times the storey height,, , 7.12.2, , For the purposes, ( see 7.11.1,7.11.2, , 7.12.2.1 Wrtica[ projection,r, , of displacement, requirements, only, and 7.11.3 only), it is permissible, , limit on design, , seismic, , force specified, , There shall be no drift limit for single storey building, which has been designed, 7.11.2 Defer-mation, A~enlhers, , to accommodate, , Conlpatibility, , Cantilever, , Projectioniv, , Tower, tanks, parapets, smoke stacks ( chimneys), and other vertical cantilever projections attached to, buildings and projecting above the roof, shall be, designed and checked for stability for five times the, design horizontal seismic coefficient Ah specified, in 6.4.2. In the analysis of the building, the weight, of these projecting elements will be lumped with the, roof weight., , to use seismic force obtained, from the computed, fundamental, period (7’) of the building without the, lower bound, in 7.8.2., , to the otherwise, , Here, i4h is as per 6.4.2., , storey drift., , of Non-Se isnlic, , 7.12.2.2, , Horizontal, , projection, , All horizontal projections like cornices and balconies, shall be designed and checked for stability for, five times the design vertical coefficient specified, , For building located in seismic Zones IV and ~ it shall, be ensured that the structural components, that are, not a part of the seismic force resisting system in the, 27

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IS 1893( Part 1 ): 2002, in 6.4.5 (that is = 10/3 A~)., , 7.12.4 Connections, , 7.12.2.3 The increased design forces specified, in 7.12.2.1 and 7.12.2.2 are only for designing the, projecting parts and their connections with the main, structures. For the design of the main structure,such, increase need not be considered., , All partsof the building, exceptbetween the separation, sections, shall be tied together to act as integrated, single unit. All connections between different parts,, such as beams to columns and columns to their, footings, should be made capable of transmitting, a force, in all possible directions, of magnitude, ( Qi/wi) times but not less t&m 0.05 times the weight, of the smaller part or the total of dead and imposed, load reaction. Frictional resistance shall not be relied, upon for fulfilling these requirements., , 7.12.3 Compound, , Walls, , Compound walls shall be designed for the design, horizontal coeftlcient Ah with importance factor, 1= 1.0 specified in 6.4.2., , Between Parts, , ., , ., , 28

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1S 1893 ( Part 1 ) :2002, , ANNEX A, ( Foreword), 68°, , 72°, , AND SURROUNDING, , SHOWING, 8, , EPICENTRES, , ,,~, , ‘, , 48o, KILOMETRES, , 32°, , c, o, , n-o, , V&,, , ~, , ~’p, , n, , ~, , RA?PUR, , 20, , 2, , o, , 1, , 16’, , 1, , 12“, , 8°, , @ Government, , of India, Copyright, , Year 2001., , Based upon Survey of India map with the permission of the Surveyor General of India., The responsibility, , for the correctness, , of internal details rests with the publisher., , The territorial waters of India extend into the sea to distance of twelve nautical miles measured from the appropriate, The administrative, , headquarters, , of Chandigarh,, , Haryana and Punjab are at Chandigarh., , The interstate boundaries between Arunachal Pradesh, Assam and Meghalaya shown on this map are as interpreted, North-Eastern Areas (Reorganization) Act, 1971, but have yet to be verified., The external boundaries, , base line., , and coastlines of India agree with the Record/Maater, 29, , Copy certified by Survay of India., , from the, , 1

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A..>.., , IS 1893( Part 1 ): 2002, , ANNEX D, (, , Foreword, , and Clause, , 3.15 ), , COMPREHENSIVE INTENSITY SCALE ( MSK 64 ), d) Intensity, , The scale was discussed generally at the intergovermnental meeting convened by UNESCO in April, 1964. Though not finally approved the scale is more, comprehensive, and describes the intensity of, earthquake more precisely. The main definitions used, are followings;, a), , Tvpe of Structures, , (Buildings), , Type.4 —, , Building in field-stone, rural, unburnt-brick, structures,, houses, clay houses., , Tvpe B —, , Ordinary brick buildings,, buildings of large block and, prefabricated type, half timbered, structures, buildings in natural, hewn stone,, , Tvpe C —, , Reinforced buildings, well built, wooden structures,, , b) Definition, , c), , Most, , About 75 percent, , Cla.~~iflcation, , of Danlage to Buildings, , Fine cracks in plaster:, fall of small pieces of, plaster., , Grade 1 Slight damage, , Grade 2 Moderate damage, , Small cracks in plaster:, fall of fairly large pieces, of plaster: pantiles slip, off cracks in chimneys, parts of chimney fall, down,, , Grade 3 Hea%ydamage, , Large and deep cracks, in plaster:, fall of, chimneys,, , Grade 4 Destruction, , Gaps in walls: parts of, buildings may collapse:, separate parts of the, buildings lose their, cohesion: and inner, walls collapse,, , Sca~e(y noticeable (very slight) — Vibration, , 3., , Weak, partially, observed, only — The, earthquake is felt indoors by a few people,, outdoors only in favorable circumstances., The vibration is like that due to the passing, of a light truck. Attentive observers notice, a slight swinging of hanging objects., somewhat more heavily on upper floors., , 4., , Largelv ob.verved — The earthquake is felt, , i), , The earthquake is felt indoors by all,, outdoors by many. Many people awake., A few run outdoors. Animals become, uneasy. Building tremble throughout., Hanging objects swing consider~bly., Pictures knock against walls or swing out, of place. Occasionally pendulum clocks, stop. Unstable objects overturn or shift., Open doors and windows are thrust open, and slam back again. Liquids spill in small, amounts from well-filled open containers., The sensation of vibration is like that, due to heavy objects falling inside the, buildipgs., , ii) Slight damages in buildings of Type A, are possible., iii) Sometimes changes in flow of springs., 33, , ., , 2., , 5. Awakening, , Total collapse of the, buildings., , Grade 5 Total damage, , Not noticeable, — The intensity of the, vibration is below the limits of sensibility:, the tremor is detected and recorded by, seismograph only., , indoors by many people, outdoors by few., Here and there people awake, but no one is, frightened. The vibration is like that due to, the passing of a heavily loaded truck., Windows, doors, and dishes rattle. Floors, and walls crack. Furniture begins to shake., Hanging objects swing slightly. Liquid in, open vessels are slightly disturbed., In, standing motor cars the shock is noticeable., , Single, few About 5 percent, About 50 percent, , 1., , is felt only by individual people at rest in, houses, especially on upper floors of, buildings., , qfQuantitv:, , Many, , Scale

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IS 1893( Part 1 ) :2002, 6., , roads on steep slopes; cracks in ground, upto widths of several centimetres. Water, in lakes become turbid. New reservoirs, come into existence. Dry wells refill and, existing wells become dry. In many cases,, change in flow and level of water is, observed., , Frightening, , i), , ii), , Felt by most indoors and outdoors. Many, people in buildings are frightened and, run outdoors. A few persons loose their, balance. Domestic animals run out of, their stalls. In few instances, dishes and, glassware may break, and books fall down., Heavy furniture may possibly move and, small steeple bells may ring., , 9., , i), , Damage of Grade 1 is sustained in single, buildings of Type B and in many of Type, A. Damage in few buildings of Type A, is of Grade 2., , Darnuge qf’ h uildingv, , i), , ii), , Most people are frightened and run, outdoors. Many find it difllcult to stand., The vibration is noticed by persons, driving motor cars. Large bells ring., In many buildings of Type C damage of, Grade 1 is caused: in many buildings of, Type B damage is of Grade 2. Most, buildings of Type A suffer damage of, Grade 3, few of Grade 4. In single, instances, landslides of roadway on steep, slopes: crack inroads; seams of pipelines, damaged; cracks in stone walls., , Destruction, , i), , of buildings, , General panic; considerable damage to, furniture. Animals run to and fro in, confusion, and cry., , iii) On flat land overflow of water, sand and, mud is often observed. Ground cracks, to widths of up to 10 cm, on slopes and, river banks more than 10 cm. Further, more, a large number of slight cracks in, ground; falls of rock, many land slides, and earth flows; large waves in water., Dry wells renew their flow and existing, wells dry up., 10. General destruction, , iii) Waves are formed on water, and is made, turbid by mud stirred up, Water levels, in wells change. and the flow of springs, changes. Some times dry springs have, their flow resorted and existing springs, stop flowing. In isolated instances parts, of sand and gravelly banks slip off., 8., , damage, , ii) Many buildings of Type C stier damage, of Grade 3, and a few of Grade 4. Many, buildings of Type B show a damage of, Grade 4 and a few of Grade 5. Many, buildings of Type A suffer damage of, Grade 5. Monuments and columns fall., Considerable damage to reservoirs;, underground pipes partly broken, In, individual cases, railway lines are bent, and roadway damaged., , iii) In few cases, cracks up to widths of, 1cm possible in wet ground in mountains, occasional landslips: change in flow of, springs and in level of well water are, observed., 7., , General, , i), , of buildings, , Fright and panic; also persons driving, motor cars are disturbed, Here and there, branches of trees break off. Even heavy, furniture moves and partly overturns., Hanging lamps are damaged in part., , of building~, , Many buildings of Type C suffer damage, of Grade 4, and a few of Grade 5. Many, buildings of Type B show damage of, Grade 5. Most of Type A have, destruction of Grade 5. Critical damage, to dykes and dams. Severe damage to, bridges. Railway lines are bent slightly., Underground pipes are bent or broken., Road paving and asphalt show waves., , ii) In ground, cracks up to widths of several, cent.imetres,sometimesup to 1m, Parallel, to water courses occur broad fissures., Loose ground slides from steep slopes., From river banks and steep coasts,, considerable landslides are possible. In, coastal areas, displacement of sand and, mud: change of water level in wells; water, from canals, lakes. rivers. etc. thrown, on land. New lakes occur., , ii) Most buildings of Type C suffer damage, of Grade 2, and few of Grade 3, Most, buildings of Type B suffer damage of, Grade 3. Most buildings of Type A suffer, damage of Grade 4. Occasional breaking, seams., Memorials and, of pipe, monuments move and twist. Tombstones, o~.erturn. Stone walls collapse., , 11, Destruction, i), , iii) Small landslips in hollows and on banked, j4, , Severe damage even to well built, buildings. bridges, water dams and

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!, IS 1893( Part 1 ) :2002, railway lines. Highways become useless, Underground pipes destroyed., , ground are, destroyed., , 12, Land.~cape changes, i), , damaged, , or, , ii) The surface of the ground is radically, changed. Considerable ground cracks, with extensive vertical and horizontal, movements are observed. Falling of rock, and slumping of river banks over wide, areas, lakes are dammed; waterfalls, appear and rivers are deflected. The, intensity of the earthquake requires to, be investigated specially., , ii) Ground considerably distorted by broad, cracks and fissures, as well as movement, in horizontal and vertical directions., Numerous landslips and falls of rocks., The intensity of the earthquake requires, to be investigated specifically,, , &, , greatly, , Practically all structures above and below, , ANNEX E, ( Foreword), ZONE FACTORS FOR SOME IMPORTANT TOWNS, Town, , Zone, , Zone Facto< Z, , Tb wn, , Zone, , Zone Facto< Z, , Chitradurga, , II, , 0.10, , Coimbatore, , HI, , 0,16, , Cuddalore, , III, , 0.16, , 0.10, , Cuttack, , 111, , 0.16, , Iv, , 0,24, , Darbhanga, , v, , 0.36, , Ambala, , IV, , 0.24, , Darjeeling, , lv, , 0.24, , Arnritsar, , Iv, , 0.24, , Dharwad, , III, , 0.16, , Asansol, , III, , 0,16, , Debra Dun, , N, , 0.24, , Aurangabad, , H, , 0.10, , Dharampuri, , III, , 0,16, , Bahraich, , w, , 0,24, , Delhi, , Iv, , 0,24, , Bangalore, , II, , 0.10, , Durfypur, , 111, , 0,16, , Barauni, , Iv, , 0.24, , Gangtok, , N, , ().24, , Bareilly, , III, , 0.16, , Guwahati, , v, , 0,36, , Belgaum, , III, , 0.16, , Goa, , 111, , 0.16, , Bhatinda, , III, , 0.16, , Gulbarga, , II, , 0.10, , Bhilai, , I1, , 0.10, , Gaya, , III, , 0.16, , Bhopal, , D, , 0.10, , Gorakhpur, , N, , 0.24, , Bhubaneswar, , 111, , 0.16, , Hyderabad, , II, , 0.10, , Blmj, , v, , 0.36, , hllphd, , v, , 0.36, , Bijapur, , III, , 0.16, , Jabalpur, , 111, , 0.16, , Bikaner, , III, , 0.16, , JaipLLr, , II, , 0.10, , Bokaro, , Agra, , III, , 0.16, , Ahmedabad, , HI, , 0.16, , Ajmer, , II, , 0,10, , Allahabad, , 11, , Ahnora, , 111, , 0.16, , Jamshedpur, , H, , 0,10, , Bulandshahr, , Iv, , 0,24, , Jhansi, , II, , 0.10, , Burdwan, , 111, , 0.16, , Jodhpur, , II, , 0.10, , Cailcut, , HI, , 0.16, , Jorhat, , v, , 0,36, , Chandigarh, , N, , ().24, , Kakrapara, , 111, , ().16, , Chcnnai, , 111, , 0.16, , Kalapakkam, , 111, , 0.16, , 35

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Bureau of Indian Standards, BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promote, harmonious development of the activities of standardization, marking and quality certification of goods and, attending to connected matters in the country., Copyright, BIS has the copyright of all its publications. No part of these publications maybe reproduced in any form without, the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the, standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to, copyright be addressed to the Director (Publications), BIS., , Review of Indian Standards, , Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed, periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are, needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards, should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue, of ‘BIS Catalogue’ and ‘Standards : Monthly Additions’., This Indian Standard has been developed from Doc : No. CED 39 ( 5341 )., Amendments, , Amend No., , Issued Since Publication, , Date of Issue, , BUREAU, , Text Affected, , OF INDIAN STANDARDS, , Headquarters:, Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002, Telephones: 3230131,3233375,3239402, , Telegrams: Manaksanstha, ( Common to all offices), , Regional Offices:, , Telephone, , Central: Manak Bhavan, 9 Bahadur Shah Zafar Marg, NEW DELHI 110002, , 3237617, { 3233841, ., , Eastern: 1/14 C. I. T. Scheme VII M, V. I. P. Road, Kankurgachi, KOLKATA 700054, , 3378499,3378561, { 3378626,3379120, , Northern: SCO 335-336, Sector 34-A, CHANDIGARH 160022, , 603843, { 602025, 2541216,2541442, { 2542519,2541315, 8329295,8327858, { 8327891,8327892, , Southern: C. I. T. Campus, IV Cross Road, CHENNAI 600113, Western : Manakalaya, E9 MIDC, Marol, Andheri (East), MUMBA1400 093, , Branches : AHMADABAD., BANGALORE., BHOPAL. BHUBANESHWAR., COIMBATORE., FARIDABAD. GHAZIABAD. GUWAHATI. HYDERABAD. JAIPUR. KANPUR., LUCKNOW. NAGPUR. NALAGARH.PATNA. PUNE. RAJKOT. THIRWANANTHAPURAM., Printed at New India Printing Press, Khrrrja, India

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AMENDMENT, , NO. 1 JANUARY 2005, TO, IS 1893 (PART 1) :2002, CRITERIA FOR, EARTHQUAKE RESISTANT DESIGN OF STRUCTURES, PART 1, , GENERAL, , PROVISIONS, , AND BUILDINGS, , ( Fifih Revision ), ( Page 5, Fig. 1 ) — Interchange ‘VARANASI’and ‘ALLAHABAD’ and ‘KOLKATA’, to bc in Zone 111., , ( Page 15, under Note 4, Table 1 ) — For Zone II, substitute the following, for the existing:, , —————, E, 1, 11(for important structures only), , ————, , ( Page, expression:, , 24, clause, , 10, , <5, 210, , 20, , ) — Substitute, , 7.6.2, , the following, , for the existing, , O09h, ‘“7, , ( Page, expression:, , 25, clause, , 7.8.4.4, , ) — Substitute, , 8S 2(1+, Pij, , the following, , B)B, , for the existing, , 1.5, , =, (1-p2f+4q2p(l+p)2, , ( Page 26, clause, , 7.9.1 ) — Delete last sentence ‘However ........ negketed’., , ( Page 26, clquse 7.9.2 ) — Renumber, following Note 2 after Note 1:, , ‘NOTE’ as ‘NOTE 1’ and add the, , ‘NOTE 2 — In case 3D dynamic analysis is earned out, the dynamic amplification factor, of 1.5 be replaced with 1.0.’, , ( Page 35, Annex E ) — Substitute the following for the existing:, ‘ Cuddalore, , II, , 0.24’, , ( CED 39 ), Reprography Unit, BIS, New Delhi, India